Process of making carbon-dioxid and solid sodium sulfite.



H. HOWARD.

PROCESS OF MAKING CARBON DI=O XID AND SOLID SODIUM SULFITE.

APPLICATION FILED NOV-22, 1915.

11,26,595 Patented May 21,1918.

HENRY HOWARD, E BROOKLINE, MASSACHUSETTS, ASSIGNOR T0 GENERAL CHEMICALcomm, A CORPORATION OF NEW YORK.

PROCESS OF KING- CARIBON DIOXID AND SOLID SODIUM SULFITE.

Specification of Letters Patent.

Original application filed March 6,1913, Serial No. 762,281. Divided andthis application filed November 22, 1915. Serial No. 62,700.

To all whom it may concern:

Be it known that I, HENRY HOWARD, a citizen of the United States,residing at Brookline, in the county of Norfolk and State ofMassachusetts, have invented certain new and useful Improvements inProcesses of Making Carbon Dioxid and Solid Sodium Sulfite, of which thefollowing is a specification.

This invention relates to a process of making carbon dioxid and solidsodium sulfite, and is an improvement upon the process described in myPatent No. 651,569, dated June 12, 1900.

The object of my invention is to make pure carbon dioxid from a suitablecarbonate, such as sodium mono-carbonate, sesqui-carbonate, orbicarbonate, or a mixture of them, or from any other alkaline 30 oralkaline-earth carbonate, under conditions which will 've a solidsulfite salt that may be utilized or other purposes, such as themanufacture of bisulfite of soda, etc.

In carrying out this process a solid carbonate of soda, orof anyother'suitable base, is added to a strong, preferably saturated,solution of sodium bisulfite,v or a bisulfite of the base in thecarbonate, in such quantities that carbon dioxid is. liberated and aneutral sulfite in the solid form is produced by the reaction betweenthem, as indicated by the following reactions With solid bicarbonate ofsoda:

This reaction, with a solid sodium carbonate, produces neutral sodiumsulfite in such excess that it also separates from the solution as afinely-divided solid sodium sulfite suspended in a saturated solution ofsodium sulfite, and may be used in making solid sodium disulfiteaccording to the process described in my prior Patent No. 1,084,436,dated January 13 1914. During the operation, it is preferable to heatthe mixture to to drive out all the carbon dioxid, otherwise some willremain dissolved in the solution of sodium sulfite, and be lost.

In the accompanying drawing, which illustrates a plant for carrying outthe process, a tank 1, provided with a valved outlet 2, supplies astrong solution of bisulfite to the bottom of the reaction tank 3; asuitable carbonate is added to tank 3 through the air-lock manhole 4,and is kept in suspension in the bisulfite solution by the strirrer 5;the mixture of bisulfite and carbonate may be heated by theheating coil6, if desired. The gas evolved by the reaction passes out through theT-outlet pipe 7, and when the reaction isover, the resulting mass ofsolid sulfite of soda and its saturated solution are removed through thebottom outlet 8. The carbon dioxid may be used as generated, or may bepurified by passing into a suitable scrubber 10 through a perforatedpipe 9. The scrubber preferably contains a solution of carbonate orbicarbonate of soda 11, which absorbs any traces of sulfur-dioxid gasthat may come from the bisulfite in tank 3. A pump 12 exhausts thedioxid from the reaction tank 3 direct by opening valve 13 and closingvalves 14 and 15; or through the scrubber by closing valve 13 andopening valves 14 and 15.

l have shown the admission of bisulfite solution to the bottom of thereaction tank 3 for the reason that bisulfites are not very stable insolution, but tend to decompose on slight heating, and on agitation. Byintroducing the bisulfite solution beneath the column of liquidcontaining the suspend carbonate, the bisulfite reacts upon the lowerstrata of carbonate, the evolved gas passing through the upper strataand in contact Patented May 21, 1918.

with more carbonate, both dissolved and suspended, whereby any sulfurdiomd will be absorbed, liberating carbon dioxid and forming neutralsulfite. The agitation of the mass not only maintains the carbonate andsulfite in suspension as above noted, but

' also facilitates and accelera the absorpwhich is formed is obtaineddirectly in solid form, the output of product from an apparatus of givensize belng correspondingly increased. The proportion of car nate addedis carefully controlled, as indicated by the foregoing equations, toavoid any excess above the amount required to yield the normal sulfite,for the reason thatany such excess, whether in solution or in susension, would contaminate the product (su fite) if intended forcommercial purposes, or would involve a correspondin loss of carbondioxid in case the sol te is treated with burner gases for re-conversioninto bisulfite in accordance with my Patent No. 1,084,436, according towhich the neutral sulfite solution containing undissolved sulfite issaturated with sulfur dioxid from burner gases or other suitable source,the resulting solid bisufite removed, and the mother liquor. utilizedfor the preparation of carbon dioxid.

I do not claim herein a process of makingpure carbon dioxid and a solidnormal sulfite in a single operation by reacting upon an aqueoussolutlon of-a bisulfite with a solid carbonate, the carbonate not inex-.

tween a soluble carbonate and a soluble bisulfite, thereby forming a.normal sulfite and carbon dioxid, purifying the carbon dioxid fromsulfur dioxid by causing the carbon dioxid to bubble throughundecomposed carbonate maintained inmechanical suspension in a liquid,said liquid in insufiicient proportion for the solution of thecarbonate, and collecting the substantially pure carbon dioxid.

' 2. The process of producing carbon dioxid, comprising effecting areaction between sodlum carbonate and dissolved sodium bisulfite,thereby forming normal sodium sulfite and carbon dioxid, purifying thecarbon dioxid from sulfur dioxid by causing the carbon dioxid to bubblethrough sodium carbonate maintained in mechanical suspension in theliquid, said liquid in insuflicient proportion for the solution of thecarbonate, and collecting the substantially pure carbon dioxid.

3. In a process of producing carbon dioxid by a reaction between sodiumcarbonate and dissolved sodium bisulfite, the step which consists inintroducing the bisulfite solution beneath the surface of a column ofliquid carrying sodium carbonate mechanically suspended therein, saidliquid in insuficient'proportion for the solution of the carbonate. 1

In testimony whereof I afix my signature in presence of two witnesses.

HENRY HOWARD.

